Continuity mistake: The amount of Kyle's facial hair changes (i.e, grows too much/fast) from the beginning of the scene when he is on the rock talking to Jaelyn to the end of the scene when he is standing in the water. Kyle's facial hair is back to its lesser amount when he is in the villa; it isn't clear how much time has passed, but it doesn't appear to be much. (00:17:06 - 00:20:28)
Continuity mistake: The straws in the three glasses in front of Abby are at different angles several times. (00:10:55)
Deliberate mistake: Abraham is sitting to the right of and slightly behind the cross he hammered into the ground, but is about 3' away. When there is a close-up, Abraham is much closer to the cross - the end of the crossbar to the right is directly above his shoulder and his knees appear to be close to the vertical bar. (00:45:15)
Continuity mistake: Simi enters the bedroom and the upper half of the bedspread is smooth. Aunt Claudia is holding a book with both hands, so she is not touching the bed. The front (somewhat aerial) view of the bed shows that the upper part of the bedspread has multiple ripples. (00:17:55 - 00:18:42)
Character mistake: We see the lead driving on the motorway to get to the cottage. She leaves at junction 6 for Princes Risborough. Which means she is on the M40 that goes to Birmingham. When she arrives the host asks about the drive down and mentions the M4. This is a different road entirely, that goes to Swansea.
Continuity mistake: The car behind Julius is at various distances. It is closer when the camera is on Julius than when it switches (back and forth) to his passenger, Margot. (00:02:39)
Plot hole: It doesn't make sense for the prosecuting attorney to agree to accept a guilty plea from Danny for assaulting an officer, possession with intent to distribute, and resisting arrest with no accompanying guilty plea for at least a lesser-included offense of murder (such as voluntary manslaughter). A violent gang member committing an initiation murder while out on parole would be dealt with much more harshly, especially when the murder victim was a high-school-aged teenager and random victim. (00:09:34)
Character mistake: Nolan said, "Everybody knows that no sharks swim in freshwater" and Spencer said, "They don't come into freshwater", but there are freshwater sharks (e.g, river sharks) and bull sharks (not true freshwater sharks) can survive in saltwater or freshwater. Jacob Harper (National Aquarium) pointed out eyewitness accounts of sharks swimming up the Mississippi River and "bull sharks have kidneys that recycle salt" but did not mention the glands near their tails that help keep salt in their bodies. (00:08:08 - 00:29:50)
Continuity mistake: The amount of wine in Annie's glass (as well as Nic's) decreases then increases without her adding any. Annie had almost one-half a glass of wine when she poured some into Nic's glass, then it was closer to one-fourth full. A little later, Annie's glass appeared to have the amount she initially had when she approached Nic. (00:13:59)
Factual error: Rose's legs were paralyzed, but when she was dragging herself on the floor, she occasionally used her feet to help propel her body forward (and moved her feet downward) - something she would not be able to do if her legs were paralyzed. (00:33:40)
Continuity mistake: Ava sees the stack of mail on the table. She sweeps her hand (fingertips and envelopes are off-screen), as she slides the top envelope closer. Ava picks up the top envelope, as if her hand sweep does not move any of the envelopes (and serves no purpose). (00:05:48)